TENS-like Stimulation Downregulates Inflammatory Cytokines in a PC-12 Cell Line

The purpose of this study was to evaluate the effects of transcutaneous electrical nerve stimulation (TENS)-like stimulation on the expression of the proinflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 in PC-12 cells, which are commonly used as neuronal cell models.

Nerve growth factor-differentiated PC-12 cells were exposed to electrical stimulation for 15 minutes at 1 mA, 200 μs, and 100 Hz. Cell lysate from stimulated and control cells was assayed for TNF-α, IL-1β, and IL-6. In 6 trials, cells were preincubated with the L-type ion channel blocker nicardipine. Cultured cells were also incubated with Alexa Fluor 488 and visualized by fluorescence microscopy to determine the nuclear vs cytoplasmic distribution of the p65 sub-unit of NF-κB RESULTS: Compared with control (unstimulated) cells, the stimulated cells had a downregulation of the assayed cytokines. However, preincubation with the L-type ion channel blocker nicardipine blocked this effect of stimulation. Additionally, it was noted that TENS-like stimulation promoted a relative sequestration of the p65 subunit of NF-κB in the cytoplasm vs the nucleus.

It appears that in this cell line and with these stimulation parameters, TENS-like stimulation attenuated the expression of the assayed proinflammatory cytokines, in part by promoting the relative sequestration of the p65 subunit of NF-κB in the cytoplasm, and that voltage-dependent calcium channels have a role in the cascade of events initiated by the TENS-like stimulation.